From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,FREEMAIL_FROM, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,7e60c1d99ae3ffa1 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-09-13 08:20:53 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!HSNX.atgi.net!cyclone-sf.pbi.net!151.164.30.35!cyclone.swbell.net!bos-service1.ext.raytheon.com!bos-service2.ext.raytheon.com.POSTED!not-for-mail Message-ID: <3D820229.E1B1BEC8@despammed.com> From: Wes Groleau Reply-To: wesgroleau@despammed.com X-Mailer: Mozilla 4.77 [en] (Windows NT 5.0; U) X-Accept-Language: en,es-MX,es,pt,fr-CA,fr MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Announce: The Ultimate SI Units Cracker References: <3D809F51.299A6634@despammed.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Fri, 13 Sep 2002 10:20:09 -0500 NNTP-Posting-Host: 151.168.144.162 X-Complaints-To: news@ext.ray.com X-Trace: bos-service2.ext.raytheon.com 1031930453 151.168.144.162 (Fri, 13 Sep 2002 11:20:53 EDT) NNTP-Posting-Date: Fri, 13 Sep 2002 11:20:53 EDT Organization: Raytheon Company Xref: archiver1.google.com comp.lang.ada:28931 Date: 2002-09-13T10:20:09-05:00 List-Id: Randy Brukardt wrote: > Wes Groleau wrote in message <3D809F51.299A6634@despammed.com>... > >Ada 95 .... allowed > >programmers to redefine/override 'Write and 'Read. I am curious > >whether overriding/creating other attributes was considered. > >Obviously, like operator overloading, it could easily be > >used to obfuscate, but it could be very useful to be able > >to define 'first and such for things like SI and Rational. > > It was considered for Ada 9x, but was rejected as having insufficient > value for the substantial changes that would be required for compilers. > Most existing Ada compilers do not put attributes in the symboltable; > they do not have visibility, and so on. But they do for 'Write & 'Read, so why not for others? > >It would also be nice to be able to define a type conversion. > > > >function Float (T : SI) return Float is .... > > This was discussed recently, and it was essentially proven to be > impossible without major incompatibilities. See ac-00026 > (http://www.ada-auth.org/cgi-bin/cvsweb.cgi/AIs/AC-00026.TXT). Thanks for the link. > >What I'm getting at is the ability to define a private type > >so that it has all the attributes and operations of a numeric > >type and can be use as a generic parameter to a numeric package. > > Someone is always dreaming about that, but no one has had anything that > looks remotely like a viable proposal. (Numeric literals are always > trouble, as are the type conversions.) I can see where literals would be difficult. But if you can declare a local type called Float, why can't you instead call a local function called Float? In the case of ambiguities.... I guess I'd better follow the link before I say any more. -- Wes Groleau http://freepages.rootsweb.com/~wgroleau